Abstract
Several microbial associations were obtained from natural and anthropogenic sources. All of the associations grow well on glucose and significantly worse on acetate. We observed 80–95% glucose consumption during 3–5 days of growth. The oxidation of substrates by the cultures generates an electric potential difference between anode and cathode electrodes of a microbial fuel cell (MFC). The value of the potential difference depends on the nature of the association and the substrate and reaches 400–500 mV. The potential difference generation accompanied by a shift to the negative region of the medium redox potential (Eh) to — (400–500) mV. This indicates H2 evolution by the association cultures during oxidation of carbohydrates. Artificial redox mediators, such as tetramethyl-p-phenylenediamine, phenazine methosulfate, and benzyl viologen, were able to increase up to 15% the difference in electrical potential across the electrodes of the MFC. It is assumed that an increase in the potential difference across the electrodes induced by the redox mediators is due to their direct involvement in the transfer of electrons from the bacteria in the incubation medium to the MFC anode electrode. The direct measurement of current and potential difference on the electrodes in a short-circuit mode shows that the internal resistance of the MFC is equal to 1 kΩ and the power reaches 5 μW. Undoubtedly, this testifies to the low efficiency developed by the MFE.
Highlights
Ïîèñê àëüòåðíàòèâíûõ âîçîáíîâëÿåìûõ èñòî÷íèêîâ ýíåðãèè ïðèâåë ê îòêðûòèþ ñïîñîáíîñòè ìèêðîîðãàíèçìîâ ãåíåðèðîâàòü ýëåêòðè÷åñêèé òîê ïðè àíàýðîáíîì îêèñëåíèè îðãàíè÷åñêèõ ñóáñòðàòîâ â óñòðîéñòâàõ, íàçâàííûõ ìèêðîáèîëîãè÷åñêèìè òîïëèâíûìè ýëåìåíòàìè (ÌÒÝ)
Ïðÿìîå èçìåðåíèå òîêà è ðàçíîñòè ïîòåíöèàëîâ íà ýëåêòðîäàõ â ðåæèìå “êîðîòêîãî çàìûêàíèÿ” ïîêàçûâàåò, ÷òî âíóòðåííåå ñîïðîòèâëåíèå ìèêðîáíîãî òîïëèâíîãî ýëåìåíòà (ÌÒÝ) ñîñòàâëÿåò ïðèáëèçèòåëüíî 1 Êîì, à ìîùíîñòü äîñòèãàåò 5 ìêÂò
Direct measurement of current and potential difference on electrodes in a mode of “short circuit” shows that the internal resistance of MFE is equal to 1 Kohm, and power reaches 5 microwatt
Summary
 êà÷åñòâå îáúåêòîâ èññëåäîâàíèÿ èñïîëüçîâàëè ïðèðîäíûå àññîöèàöèè ìèêðîîðãàíèçìîâ, âûäåëåííûå èç îáðàçöîâ ïî÷âû è èëà: 1) òîðô èç âåðõîâîãî áîëîòà Òâåðñêîé îáë. (ÒA); 2) èë îòñòîéíèêà ìåòàëëóðãè÷åñêîãî ïðåäïðèÿòèÿ Òóëà÷åðìåò (ÒÈÎ); 3) ëå÷åáíûé èë îç. 1, ÐÝÏ ìåæäó àíîäíûì è êàòîäíûì ýëåêòðîäàìè ÌÒÝ ñ ìèíóñîì íà àíîäå áûñòðî íàðàñòàåò è äîñòèãàåò ÷åðåç 50—100 ìèí èíêóáàöèè êóëüòóðû ÒÀ (ïðè ïåðåõîäå íà ñòàöèîíàðíûé óðîâåíü) ìàêñèìàëüíûõ çíà÷åíèé â ðàéîíå –400 ìÂ. 1. Èçìåíåíèÿ ÐÝÏ ìåæäó àíîäîì è êàòîäîì ÌÒÝ (1) è Eh ñðåäû (2) â äèíàìèêå ðàçâèòèÿ êóëüòóðû ÒÀ íà ñðåäå ñ ãëþêîçîé. ÐÝÏ è âåëè÷èíà Eh ñðåäû äëÿ êóëüòóð àññîöèàöèé ÒÀ, ÈÎÌ è ÒÈÎ íà ñðåäå ñ ãëþêîçîé äîñòèãàþò âûñîêèõ çíà÷åíèé, òîãäà êàê äëÿ àññîöèàöèè ÁÀ âåëè÷èíû ýòèõ ïàðàìåòðîâ çíà÷èòåëüíî íèæå. Ñ îäíîé ñòîðîíû, ðàçíîñòü ïîòåíöèàëîâ â 1,5—2 ðàçà íèæå ïî ñðàâíåíèÿ ñ òàêîâîé íà ñðåäå ñ ãëþêîçîé, à ñ äðóãîé — âåëè÷èíà ðåäîêñ-ïîòåíöèàëà ñðåäû íå òîëüêî êàðäèíàëüíî ñîêðàùàåòñÿ ïî àáñîëþòíîìó çíà÷åíèþ â ïðîöåññå èíêóáàöèè êóëüòóð ñ àöåòàòîì (çà èñêëþ÷åíèåì êóëüòóðû ÒÀ), íî ïåðåõîäèò â îáëàñòü ïîëîæèòåëüíûõ çíà÷åíèé (òàáëèöà). Âåëè÷èíà ðàçíîñòè ïîòåíöèàëîâ ìåæäó àíîäîì è êàòîäîì ÌÒÝ, à òàêæå Eh ñðåäû ïðè äîñòèæåíèè ñòàöèîíàðíîãî ñîñòîÿíèÿ
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